c++和java字节高低位的转换.doc

c+和java字节高低位的转换现在我们需要从一个C/C+语言生成的二进制文件中读出一个float数据1. /参见java.io.DataInputStream2. /C+写入的字节顺序是从低到高（左低到右高），3. 而java.io.DataInputStream读取的数据是从高到低（左高到右低)4. /所以需要自己改写一下5. /功能和java.io.DataInputStream类似的6. publicclassCppInputStreamextendsFilterInputStream7. 8. publicCppInputStream(InputStreamin)9. super(in);10. 11. publicfinalintread(byteb)throwsIOException12. returnin.read(b,0,b.length);13. 14. 15. publicfinalintread(byteb,intoff,intlen)throwsIOException16. returnin.read(b,off,len);17. 18. 19. publicfinalvoidreadFully(byteb)throwsIOException20. readFully(b,0,b.length);21. 22. 23. publicfinalvoidreadFully(byteb,intoff,intlen)throwsIOException24. if(len0)25. thrownewIndexOutOfBoundsException();26. intn=0;27. while(nlen)28. intcount=in.read(b,off+n,len-n);29. if(count0)30. thrownewEOFException();31. n+=count;32. 33. 34. 35. publicfinalintskipBytes(intn)throwsIOException36. inttotal=0;37. intcur=0;38. while(total0)39. total+=cur;40. 41. returntotal;42. 43. 44. publicfinalbytereadByte()throwsIOException45. intch=in.read();46. if(ch0)47. thrownewEOFException();48. return(byte)(ch);49. 50. 51. publicfinalintreadUnsignedByte()throwsIOException52. intch=in.read();53. if(ch0)54. thrownewEOFException();55. returnch;56. 57. 58. publicfinalshortreadShort()throwsIOException59. intch2=in.read();60. intch1=in.read();61. if(ch1|ch2)0)62. thrownewEOFException();63. return(short)(ch18)+(ch20);64. 65. 66. publicfinalintreadUnsignedShort()throwsIOException67. intch2=in.read();68. intch1=in.read();69. if(ch1|ch2)0)70. thrownewEOFException();71. return(ch18)+(ch20);72. 73. 74. publicfinalcharreadChar()throwsIOException75. intch2=in.read();76. intch1=in.read();77. if(ch1|ch2)0)78. thrownewEOFException();79. return(char)(ch18)+(ch20);80. 81. 82. publicfinalintreadInt()throwsIOException83. intch4=in.read();84. intch3=in.read();85. intch2=in.read();86. intch1=in.read();87. if(ch1|ch2|ch3|ch4)0)88. thrownewEOFException();89. return(ch124)+(ch216)+(ch38)+(ch40);90. 91. 92. privatebytereadBuffer=newbyte8;93. 94. publicfinallongreadLong()throwsIOException95. readFully(readBuffer,0,8);96. return(long)readBuffer756)+(long)(readBuffer6&255)48)97. +(long)(readBuffer5&255)40)+(long)(readBuffer4&255)32)98. +(long)(readBuffer3&255)24)+(readBuffer2&255)16)99. +(readBuffer1&255)8)+(readBuffer0&255)0);100. 101. 102. publicfinalfloatreadFloat()throwsIOException103. returnFBitsToFloat(readInt();104. 105. 106. publicfinaldoublereadDouble()throwsIOException107. returnDouble.longBitsToDouble(readLong();108. 109. yy629(资深程序员) 2010-05-12简单呀，用Java的字节流，读取一个int的4个字节，然后转换。比如读取的数据是：byte1 byte2 byte3 byte4在其实这是C+的 byte4 byte3 byte2 byte1那你可以用位运算转成Java中的对应的整数：(byte1& 0xff)0 + (byte2& 0xff)8 + (byte3& 0xff) 16 +(byte4& 0xff)8);7. bytebyte2=(byte)(javaReadInt&0xff0000)16);8. bytebyte1=(byte)(javaReadInt&0xff000000)24);9. 10. /拼装成正确的int11. intrealint=(byte1&0xff)0+(byte2&0xff)8+(byte3&0xff)16+(byte4&0xff)24;另外可以使用ByteBuffer来完成,而不需要自己考虑,如何将字节数组转换为其他数据类型. 使用ByteBuffer,可以设置字节顺序.ByteBuffer简单的例子import java.nio.ByteBuffer;import java.nio.ByteOrder;public class ByteBufferTest public static void main(String args) /将字节数组转换为int类型 byte bytes = 0,0,0,1; ByteBuffer buffer = ByteBuffer.wrap